The Relationship between Motor Skills and Intelligence in Children with Autism Spectrum Disorder

Global developmental delay: comparison of developmental profiles between gene-positive/suspicious positive and gene-negative cases

BACKGROUND

Global developmental delay (GDD) is associated with genetic abnormalities; however, the specific clinical and developmental features that should trigger genetic testing remain unclear. In this study, we explored this issue.

METHODS

A total of 126 children with GDD were recruited for this study. Comprehensive medical histories and physical examination data were collected for all participants. The Chinese adaptation of the Griffiths Mental Development Scales was used to assess neurodevelopmental outcomes. Genetic variations were analyzed through trio-based whole exome sequencing and proband whole genome sequencing. A comparative analysis of the clinical characteristics was conducted between children with gene-positive/suspicious positive results (i.e., the mutation is deleterious or potentially deleterious, and the inheritance pattern and phenotype are matched) and those with negative results.

RESULT

The positive/suspicious positive rate of genes was 46.8%. The locomotor, performance, and general quotients were lower in the gene-positive/suspicious positive group than the gene-negative group (p < 0.05), and the lower the locomotor ability, the higher the gene positive/suspicious positive rate (p < 0.05).

CONCLUSION

Children with GDD and genetic abnormalities exhibited poorer locomotor, performance, and general developmental quotients compared to those without genetic mutations. Furthermore, individuals with poorer locomotor ability should be prioritized for genetic testing.

IMPACT

This study aimed to compare the clinical and developmental profiles of children with GDD who test positive or suspiciously positive for genetic abnormalities with those who test negative, and to identify key clinical features that may serve as indicators for genetic testing. It highlights that children with GDD and genetic abnormalities exhibited poorer locomotor, performance, and general developmental quotients compared to those without genetic mutations. Individuals with poorer locomotor ability should be prioritized for genetic testing. The findings supplement existing literature by providing insights to guide clinicians on determining which children with GDD should be considered for genetic testing.

Prevalence of Motor Milestone Delays in Autistic Children

Importance

Prior literature has explored the prevalence of motor impairments in autistic individuals, but estimates come from clinical, convenience, or small samples, limiting generalizability. Better understanding of the frequency of motor milestone delays in autistic individuals could improve early identification and subsequently lead to earlier intervention and better developmental outcomes.

Objective

To determine the prevalence of motor milestone delays in a population-based sample of 8-year-old autistic children and to evaluate if having motor milestone delays is associated with an earlier age at autism evaluation or diagnosis.

Design, Setting, and Participants

This cross-sectional study of autistic 8-year-old children was conducted using Autism and Developmental Disabilities Monitoring (ADDM) Network data between surveillance years 2000 and 2016. ADDM Network data are population based and are drawn from 17 sites across the US. Data were analyzed from October 2023 to August 2024.

Exposure

Binary indicator of motor milestone delays documented in health or educational records.

Main Outcomes and Measures

The primary outcome was the prevalence of motor milestone delays among autistic 8-year-old children. Associations between motor milestone delays and age at autism evaluation or diagnosis were evaluated using linear regression. Covariates included study site, surveillance year, the number of autism discriminators, intellectual disability, child sex, and child race and ethnicity.

Results

Among 32 850 children aged 8 years identified with autism by active surveillance, 23 481 children (71.5%) met criteria for motor milestone delays. A total of 5973 children (18.2%) were female. In linear regression models, children with motor milestone delays were evaluated for autism significantly earlier (mean age, 43.65 months; 95% CI, 43.38-43.91) than children without motor milestone delays (mean age, 51.64 months; 95% CI, 51.22-52.06). After stratifying by the co-occurrence of intellectual disability (ID), children with motor milestone delays were evaluated for autism earlier than those without motor milestone delays, regardless of ID.

Conclusions and Relevance

This cross-sectional study estimates the prevalence of motor milestone delays among autistic 8-year-old children and highlights the association between these delays and an earlier autism evaluation, even in children without co-occurring ID. Early identification of autism is a public health priority, and assessing motor milestone delays, particularly in children with an increased likelihood of being autistic, may facilitate an earlier autism evaluation, leading to more timely interventions and better developmental outcomes.

Sensorimotor Features and Daily Living Skills in Autistic Children With and Without ADHD

Attention-deficit/hyperactivity disorder (ADHD) commonly co-occurs in autistic children. However, additional research is needed to explore the differences in motor skills and sensory features in autistic children with and without ADHD, as well as the impacts of these factors on daily living skills (DLS). This observational study sought to fill this gap with 67 autistic children (6.14-10.84 years-old), 43 of whom had ADHD. Autistic children with ADHD demonstrated higher sensory features and lower motor skills than autistic children without ADHD. In examining autism and ADHD features dimensionally, we found that overall sensory features, seeking, and hyporesponsiveness were driven by both autism and ADHD features, whereas motor skills, enhanced perception, and hyperresponsiveness were driven by only autism features. Additionally, in using these dimensional variables of autism and ADHD features, we found that differences in motor skills, sensory and autism features, but not ADHD features, impact DLS of autistic children, with autism features and motor skills being the strongest individual predictors of DLS. Together, these results demonstrate the uniqueness of motor skills and sensory features in autistic children with and without ADHD, as well as how autism features, sensory features, and motor skills contribute to DLS, emphasizing the importance of a comprehensive understanding of each individual and complexities of human development when supporting autistic children.

Motor Competence in Autistic Children with Attention-Deficit Hyperactivity Disorder

BACKGROUND/OBJECTIVES

Children with autism exhibit deficits in fundamental motor skills, which are intensified when associated with attention-deficit/hyperactivity disorder (ADHD).

OBJECTIVE

To correlate motor competence in children with autism, autism levels according to the CARS scale, and the association with ADHD.

METHODS

This cross-sectional study assessed motor competence using the Motor Competence Assessment (MCA), the severity of Autism Spectrum Disorder by Childhood Autism Rating Scale (CARS), and the presence of clinical signs for ADHD using Swanson, Nolan, and Pelham (SNAP-IV) questionnaire. A total of 68 children were recruited; however, 23 were not included due to non-acceptance and/or were excluded because of associated pathologies, high autism severity. Consequently, 45 children (11 with ADHD) between the ages of 5 and 11 (Mean: 8.15; ±1.75) with 83.72% being male.

RESULTS

Multiple linear regression revealed a significant inverse correlation between MCA scores and raw CARS data (p = 0.01), indicating that greater autism severity is associated with lower motor competence. The correlation was also observed in CARS classifications, with higher autism severity corresponding to lower motor percentiles (p = 0.05). However, the correlation between the presence of ADHD and motor competence in children with ASD did not reach significance. Overall, a significant correlation was observed (p = 0.006) when analyzing all variables (CARS scores, SNAP scores, and CARS classification).

CONCLUSION

Therefore, it is believed that children with autism exhibit deficits in functional motor skills, with severity impacting motor competence. The findings underscore the need for systematic motor skill assessments in children with autism, emphasizing the importance of monitoring and intervention in this aspect of their development.

Enhanced motor noise in an autism subtype with poor motor skills

BACKGROUND

Motor difficulties are common in many, but not all, autistic individuals. These difficulties can co-occur with other problems, such as delays in language, intellectual, and adaptive functioning. Biological mechanisms underpinning such difficulties are less well understood. Poor motor skills tend to be more common in individuals carrying highly penetrant rare genetic mutations. Such mechanisms may have downstream consequences of altering neurophysiological excitation-inhibition balance and lead to enhanced behavioral motor noise.

METHODS

This study combined publicly available and in-house datasets of autistic (n = 156), typically-developing (TD, n = 149), and developmental coordination disorder (DCD, n = 23) children (age 3-16 years). Autism motor subtypes were identified based on patterns of motor abilities measured from the Movement Assessment Battery for Children 2nd edition. Stability-based relative clustering validation was used to identify autism motor subtypes and evaluate generalization accuracy in held-out data. Autism motor subtypes were tested for differences in motor noise, operationalized as the degree of dissimilarity between repeated motor kinematic trajectories recorded during a simple reach-to-drop task.

RESULTS

Relatively 'high' (n = 87) versus 'low' (n = 69) autism motor subtypes could be detected and which generalize with 89% accuracy in held-out data. The relatively 'low' subtype was lower in general intellectual ability and older at age of independent walking, but did not differ in age at first words or autistic traits or symptomatology. Motor noise was considerably higher in the 'low' subtype compared to 'high' (Cohen's d = 0.77) or TD children (Cohen's d = 0.85), but similar between autism 'high' and TD children (Cohen's d = 0.08). Enhanced motor noise in the 'low' subtype was also most pronounced during the feedforward phase of reaching actions.

LIMITATIONS

The sample size of this work is limited. Future work in larger samples along with independent replication is important. Motor noise was measured only on one specific motor task. Thus, a more comprehensive assessment of motor noise on many other motor tasks is needed.

CONCLUSIONS

Autism can be split into at least two discrete motor subtypes that are characterized by differing levels of motor noise. This suggests that autism motor subtypes may be underpinned by different biological mechanisms.

Objective measurement of movement variability using wearable sensors predicts ASD outcomes in infants at high likelihood for ASD and ADHD

Early motor delays and differences are common among children with autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). Yet, little work has shown whether there are early atypical motor signs that differentiate these groups. Quantitative measures of movement variability hold promise for improving the identification of subtle and specific differences in motor function among infants and toddlers at high likelihood for ASD and ADHD. To this end, we created a novel quantitative measure of movement variability (movement curvature) and conducted a preliminary investigation as to whether this measure improves outcome predictions. We used a wearable triaxial accelerometer to evaluate continuous motion-based activity in infants at high and low likelihood for ASD and ADHD at 12, 18, 24, and 36 months of age. At 36 months, participants were categorized into three outcome groups: ASD (n = 19), ADHD concerns (n = 17), and a comparison group (n = 82). We examined group differences in movement curvature and whether movement curvature is predictive of a later ASD or ADHD concerns classification. We found that movement curvature was significantly lower in infants with later ASD diagnosis at 18, 24, and 36 months of age compared to infants with either ADHD concerns or those in the comparison group. Movement curvature was also a significant predictor of ASD at 18, 24, and 36 months (AUC 0.66-0.71; p = 0.005-0.039) and when adjusting for high ASD likelihood at 18 and 24 months (AUC 0.90, p = 0.05-0.019). These results indicate that lower movement curvature may be a feature of early motor differences in infants with later ASD diagnosis as early as 18 months of age.

The relation between specific motor skills and daily living skills in autistic children and adolescents

Introduction

Motor skill difficulties are common in autistic children and are related to daily living skills (DLS). However, it remains unclear which specific motor tasks are most likely to impact overall DLS. This study sought to fill this gap.

Methods and results

In 90 autistic children and adolescents (ages 6-17 years), we found that fine/manual motor tasks, like drawing or folding, demonstrated significant medium-sized relations with DLS, even after accounting for IQ and sensory features, whereas tasks in the areas of bilateral coordination, upper-limb coordination, and balance only related to DLS (small effect sizes) prior to accounting for IQ and sensory features. When looking at an overall balance score, we found that IQ significantly interacted on the relation between overall balance and DLS.

Discussion

These results further demonstrate the particular importance of fine/manual motor skills for DLS in autistic youth, even when accounting for IQ and sensory features. Indeed, accounting for sensory features strengthened the relations between fine/manual motor skills and DLS. Our findings provide evidence of the impact of cognitive factors on the relation between balance and DLS, indicating that it may be that autistic individuals with lower IQs experience relations between balance and DLS that are different than their peers with higher IQs. Our findings support the benefit of considering individual motor skills rather than domain-level information when assessing ways to promote DLS in autistic youth. The results further shed light on the importance of fine motor skills, as well as the unique relationship of balance and DLS in autistic individuals with lower IQs.

Comparing fine motor performance among young children with autism spectrum disorder, intellectual disability, attention-deficit/hyperactivity disorder, and specific developmental disorder of motor function

Objective

The acquisition of fine motor skills is considered to be a crucial developmental milestone throughout early childhood. This study aimed to investigate the fine motor performance of young children with different disability diagnoses.

Methods

We enrolled a sample of 1,897 young children under the age of 6 years who were at risk of developmental delays and were identified by a transdisciplinary team. A series of standardized developmental assessments included the Bayley Scales of Infant Development-Third Edition, Wechsler Preschool and Primary Scale of Intelligence-Fourth Edition, Peabody Developmental Motor Scale-Second Edition, and Movement Assessment Battery for Children-Second Edition were used. Retrospective chart reviews were conducted on all children to identify specific developmental disorders. The number of autism spectrum disorder (ASD), intellectual disability (ID), attention-deficit/hyperactivity disorder (ADHD), comorbidity, motor dysfunction, and unspecified developmental delays (DD) were 363 (19.1%), 223 (11.8%), 234 (12.3%), 285 (15.0%), 128 (6.7%), and 590 (31.1%), respectively.

Results

Young children with ID, comorbidity, and motor dysfunction demonstrated significant difficulty in performing manual dexterity and visual motor integration tasks and scored significantly lower in these areas than children with ASD, ADHD, and unspecified DD. In addition, fine motor performance was associated with cognitive ability in children with different disability diagnoses, indicating that young children showed better fine motor performance when they demonstrated better cognitive ability.

Conclusion

Our findings support that differences in fine motor performance differ by disability type. Close links between fine motor performance and cognitive ability in children under the age of 6 years were seen in all disability types.

Intellectual development in young children with autism spectrum disorders: A longitudinal study

Intelligence profiles in autism have been characterized by great variability. The questions of how autistic children's intelligence changes over time, and what factors influence these changes deserve study as part of efforts to document child autism profiles, but also because the relationship between intellectual functioning and children's background characteristics is poorly understood, particularly in a longitudinal context. A total of 39 autistic children and 39 age-matched neurotypical children (5-9 years old) completed two IQ assessments at preschool age and up to 4 years later. Repeated-measures analyses assessed longitudinal changes in the children's verbal (VIQ), performance (PIQ), and full-scale IQ (FSIQ) at group level. We further sought to identify clusters with distinct profiles in each group by adopting an unsupervised K-means clustering approach, and detect possible between-subgroup differences in terms of children's socioeconomic status and autism severity. The largest cluster in the autistic group was composed of children whose PIQ significantly dropped at follow-up, while the second largest cluster improved in all quotients; the smallest cluster, wherein children had more highly educated mothers than the rest of the clusters, was characterized by large improvement in VIQ. For the neurotypical children, there was a two-cluster division; the majority of them improved in the three quotients, while very few dropped in PIQ at follow-up. The relation between socioeconomic status and IQ changes was significant for both groups. The findings demonstrate both the complexity of intelligence changes in autism and the need to view this complexity through the lens of the children's socioeconomic diversity.

The role of SCAMP5 in central nervous system diseases

OBJECTIVE

Secretory carrier membrane proteins (SCAMPs) constitute a group of membrane transport proteins in plants, insects and mammals. The mammalian genome contains five types of SCAMP genes, namely, SCAMP1-SCAMP5. SCAMPs participate in the vesicle cycling fusion of vesicles and cell membranes and play roles in regulating exocytosis and endocytosis, activating synaptic function and transmitting nerve signals. Among these proteins, SCAMP5 is highly expressed in the brain and has direct or indirect effects on the function of the central nervous system. This paper may allow us to better understand the role of SCAMP5 in the central nervous system diseases. SCAMP5 regulates membrane transport, controls the exocytosis of SVs and is related to secretion carrier and membrane function. In addition, SCAMP5 plays a major role in the normal maintenance of the physiological functions of nerve cells. This article summarizes the effects of SCAMP5 on nerve cell exocytosis, endocytosis and synaptic function, as well as the relationship between SCAMP5 and various neurological diseases, to better understand the role of SCAMP5 in the pathogenesis of neurological diseases.

METHODS

Through PubMed, this paper examined and analyzed the role of SCAMP5 in the central nervous system, as well as the relationship between SCAMP5 and various neurological diseases using the key terms "secretory carrier membrane proteins"," SCAMP5"," exocytosis"," endocytosis", "synaptic function", "central nervous system diseases" up to 01 March 2022.

RESULTS

SCAMP5 regulates membrane transport, controls the exocytosis of SVs and is related to secretion carrier and membrane function. In addition, SCAMP5 plays a major role in the normal maintenance of the physiological functions of nerve cells.

CONCLUSION

This article summarizes the effects of SCAMP5 on nerve cell exocytosis, endocytosis and synaptic function, as well as the relationship between SCAMP5 and various neurological diseases, to better understand the role of SCAMP5 in the pathogenesis of neurological diseases.

Retained Primitive Reflexes and Potential for Intervention in Autistic Spectrum Disorders

We provide evidence to support the contention that many aspects of Autistic Spectrum Disorder (ASD) are related to interregional brain functional disconnectivity associated with maturational delays in the development of brain networks. We think a delay in brain maturation in some networks may result in an increase in cortical maturation and development in other networks, leading to a developmental asynchrony and an unevenness of functional skills and symptoms. The paper supports the close relationship between retained primitive reflexes and cognitive and motor function in general and in ASD in particular provided to indicate that the inhibition of RPRs can effect positive change in ASD.

Quantitative Assessment of Sensory Integration and Balance in Children with Autism Spectrum Disorders: Cross-Sectional Study

Postural stability is dependent on the interpretation of external inputs acquired by sensory information processes, such as visual, vestibular, and proprioceptive systems, in order to accomplish neuromuscular control, balance maintenance, and appropriate motor response. A defect in any of these systems, or in the integration of information given by these systems, might threaten their capacity to maintain balance. Therefore, the purpose of this study was to investigate the sensory integration and balance using the Biodex balance system (BBS) in children with autism spectrum disorder (ASD) during the static posture. Seventy-four children from both sexes, 38 with ASD matched with 36 typically developed (TD) children as a control group, were included in the study. Using the Biodex balance system, the postural sway was evaluated through the modified Clinical Test of Sensory Integration and Balance (m-CTSIB) during quiet standing. In this test, four different situations were considered from standing position: eyes open/firm surface, eyes closed/firm surface, eyes open/foam surface, and eyes closed/foam surface. ASD children showed a significant increase in postural sway under all tested conditions when compared to the TD children group, especially for the conditions in which visual and somatosensory inputs were disrupted (p-value < 0.05). These results provide evidence that postural stability decreased in ASD children. Under static postural challenges, the current study’s findings imply that children diagnosed with ASD have postural control deficiencies, especially for the conditions in which visual and somatosensory input was disrupted. Further research must be conducted to find the best balance training program for ASD cases using the Biodex balance system and considering its impact on motor skills.

Motor impairments in Chinese toddlers with autism spectrum disorder and its relationship with social communicative skills

OBJECTIVE

Motor impairments are prevalent in children with autism spectrum disorder (ASD) and persistent across age. Our current study was designed to investigate motor deficits in Chinese toddlers with ASD and to explore the relationships between motor deficits and social communication skills.

METHODS

For this cross-sectional study, we recruited a total of 210 Chinese toddlers with ASD aged between 18 and 36 months in the study during December 2017 to December 2020. Griffiths Developmental Scales-Chinese (GDS-C), Autism Diagnostic Observation Schedule-Second Edition (ADOS-2) and Communication and Symbolic Behavior Scales Developmental Profile-Infant-Toddler Checklist (CSBS-DP-ITC) were administered in these toddlers to evaluate their development, social communicative skills, and autism severity. We compared the developmental and social communicational profiles of ASD toddlers in different gross and fine motor subgroups, and explored potential associated factors. The univariate generalized linear model tested the relationship of fine and gross motor skills and social communicative skills.

RESULTS

The prevalence of gross and fine motor deficits were 59.5 and 82.5%, respectively, which are almost equivalent in boys and girls. The motor impairments tended to be more severe with age in toddlers. After adjusting for age, sex, non-verbal development quotient (DQ) and restricted, repetitive behaviors, severer gross motor impairments were significantly related to higher comparison score of ADOS-2 and higher social composite score of CSBS-DP-ITC, without interactions with other variables. Meanwhile, lower fine motor skills were associated with more deficits of social communication and higher severity of ASD, also depending on non-verbal DQ. In the lower non-verbal DQ subgroup, both fine motor deficits and restricted repetitive behaviors (RRBs) might have effects on autism symptomology.

CONCLUSION

Motor impairments are common in Chinese toddlers with ASD. Toddlers with weaker gross and fine motor skills have greater deficits in social communicative skills. Gross motor impairment might be an independent predictor of the severity of autism and social communication skills, while the effect of fine motor deficits might be affected by non-verbal DQ and RRBs of toddlers with ASD. We provide further justification for the inclusion of motor impairments in the early intervention for toddlers with ASD.

Motor Skill Differences in Autism Spectrum Disorder: a Clinically Focused Review

PURPOSE OF REVIEW

This review synthesizes recent, clinically relevant findings on the scope, significance, and centrality of motor skill differences in autism spectrum disorder (ASD).

RECENT FINDINGS

Motor challenges in ASD are pervasive, clinically meaningful, and highly underrecognized, with up to 87% of the autistic population affected but only a small percentage receiving motor-focused clinical care. Across development, motor differences are associated with both core autism symptoms and broader functioning, though the precise nature of those associations and the specificity of motor profiles to ASD remain unestablished. Findings suggest that motor difficulties in ASD are quantifiable and treatable, and that detection and intervention efforts targeting motor function may also positively influence social communication. Recent evidence supports a need for explicit recognition of motor impairment within the diagnostic framework of ASD as a clinical specifier. Motor differences in ASD warrant greater clinical attention and routine incorporation into screening, evaluation, and treatment planning.